Drama has two aspects - as a literary composition and as a performance on stage. It presents a story entirely through dialogue and action. The key elements of drama include setting, characters, plot, theme and style. Settings identify the time and place of events. Characters have physical, social, psychological and moral aspects. Plots involve a beginning, middle and ending, with events structured as either natural or episodic sequences. Themes convey the central idea, while style refers to the mode of presentation. Common genres include tragedy, comedy, tragicomedy, farce and melodrama.